Pump driven by an electromotor and method for producing a pump of this type

ABSTRACT

The invention relates to a pump ( 10 ), having a pump head ( 12 ), which has a pump chamber ( 11 ), and having an electric motor ( 14 ), which drives the pump head ( 12 ) and has a stator ( 40 ) and a rotor ( 38 ), the rotor ( 38 ) being connected to the pump head ( 12 ) and being disposed in a rotor chamber ( 82 ) open toward the pump chamber ( 11 ).  
     It is proposed that the stator ( 40 ) is disposed radially around the rotor chamber ( 82 ), and the rotor chamber ( 82 ) is sealed off from the pump chamber ( 11 ) by a sealing wall ( 51 ) belonging to the stator ( 40 ) and by at least one wall ( 64 ) of the pump housing ( 18 ).

PRIOR ART

[0001] The invention is based on a motor pump having a pump head and an electric motor that drives the pump head, as generically defined by the preamble to claim 1, and to a method for producing such a pump, as generically defined by the preamble to claim 20.

[0002] Such motor pumps serve to transport or increase the pressure of a fluid and have long been used, for instance as water pumps in heating circuits.

[0003] From European Patent EP-0 778 649 B1, a pump-motor unit is known, which acts as a coolant pump of a motor vehicle internal combustion engine. The pump-motor unit described in EP-0 778 649 B1 is a centrifugal pump, which is driven by an electronically commutated direct-current motor. The centrifugal pump and the direct-current motor are connected to one another via a radiator. Fastened between the pump housing and the radiator is a split pot, made of a suitable material, which separates the rotor of the electric motor from the stator. A seal placed between the pump housing and the split pot seals off the fluid-filled rotor chamber from an outer stator chamber.

[0004] One disadvantage of the pump-motor unit described in EP-0 778 649 B1 and of all comparable motor pumps is the existing air gap between the stator and the rotor of the electric motor, which adversely affects the efficiency of a split tube motor of this kind. Reducing the air gap by lessening the thickness of the material of the split pot has the risk of mechanical instabilities of the split pot. This can cause premature failure of the pump.

[0005] Cooling the power electronics of the control motor by means of an additional passive radiator, as proposed in EP-0 778 649 B1-besides requiring one additional split pot increases the complexity of such a pump.

[0006] In EP 0 713 282 B1, a split tube motor for pumps is disclosed, with a split pot disposed between the rotor and the stator. The rotor has a thin-walled, sleevelike and in particular laminated base body. On its outside, this base body has radially oriented ribs, which carry the stator winding, and with its cylindrical inside, it rests at least partly on the outside of the split tube. Once again, the complex assembly and sealing of the additional split pot is a disadvantage. The split tube must be built in and sealed off between the stator packet and the rotor.

[0007] The open- and closed-loop control electronics of the split tube motor of EP-0 713 282 is embodied as a module and requires complicated cooling. The electronic module rests with one side of its housing by positive engagement on the stator winding. The heat energy generated by the electronics is given off via the switch housing to the motor housing, with the stator winding located inside it. The stator winding in turn gives up the heat energy it has absorbed to the pumping medium via the split pot.

ADVANTAGES OF THE INVENTION

[0008] The pump of the invention having the characteristics of claim 1 has the advantage that in a simple way, it becomes possible to seal off the rotor chamber, which is open toward the pumping medium, from the stator chamber, and good cooling of the electronics of the pump motor is achieved as well.

[0009] Because the sealing wall of the split pot belongs directly to the stator, it is possible to dispense with a split tube as an additional component. In the assembly and sealing off of the pump of the invention, the assembly step of introducing the split tube between the stator and the rotor is dispensed with, leading to a corresponding simplification and cost reduction for the production of the pump of the invention.

[0010] By the provisions recited in the dependent claims, advantageous refinements of and improvements to the pump recited in claim 1 are possible.

[0011] One advantageous feature of the pump of the invention is obtained by providing that the pump head, the electric motor driving this pump head, and an electronic switch mechanism that serves to control the electric motor are disposed in common in a housing. This housing can be a one-piece housing or can comprise multiple components that are to be associated with the various functions (pump, motor, switch mechanism) and are connected to one another. The motor housing can thus be used simultaneously as a housing part and as a radiator for the electronics.

[0012] A wall embodied integrally with the motor housing lends the pump of the invention the requisite mechanical stability and can at the same time contribute to sealing off the rotor chamber. In particular, this wall can be produced of metal, which has advantages in terms of strength and heat transfer. In principle, it is thus possible to use only a single metal part for the pump housing of the pump of the invention, which makes for a marked cost reduction for such a pump.

[0013] A sealing wall solidly joined to the stator and defining the rotor chamber radially averts the necessity of a split tube in the form of an additional, separate component. For sealing between the rotor and the stator, a separate part is accordingly no longer necessary. In particular, this sealing wall can be embodied as a casing of the stator that is completely closed in the circumferential direction of the rotor chamber. This casing of the stator can advantageous be produced from plastic or some other suitable material.

[0014] Encasing the stator with a plastic furthermore offers the advantage that the stator pole teeth, which can for instance be formed by discrete sheet-metal lamination packets, can simply and advantageously be injected directly into the plastic and thus fixed. By means of the plastic casing, it is furthermore possible for the sealing element between the rotor chamber and the stator chamber to be assigned a number of additional functions, which a separate split tube in its original sense cannot perform. Besides sealing off the rotor chamber that carries the pumping medium from the stator chamber, the stator lamination packets can be secured by the injection and for instance secured against rotation. This means a simple, secure fixation of the lamination packets. The spray-coated stator also makes it possible for the requisite winding bodies of the stator winding to be jointly embodied directly in the injection-molding process. Contact pockets required for connecting the stator winding can accordingly, like other required retaining means on the stator, advantageously be formed directly in the injection molding process. All of this makes the structure and sealing of the stator simpler, reduces the number of components, and thus facilitates the assembly of the pump of the invention. With a split tube pump of the conventional design, this is not feasible.

[0015] If the stator is connected to a motor housing wall, in particular a metal wall, then this wall can absorb the incident forces and moments. This metal wall, because of its thermal conductivity, can then also expediently be used directly as a radiator for the electronics of the pump motor. Good cooling of the electronic switch elements is obtained if these elements are mounted directly on the metal wall. A heat conduction foil can optionally be placed between the component and the radiator as well. It is conceivable for the power components of the electronics to be pressed against the cooling surface by way of springs, or to be coupled thermally directly with the cooling surface via an electrically insulating adhesive. This assures good heat transfer from the power component of the electronics into the metal motor housing.

[0016] A further marked improvement in cooling of the elements of the control electronics can be attained if the metal cooling wall is in turn additionally cooled actively. In the motor pump of the invention, some of the fluid to be pumped is therefore carried past the cooling wall toward the motor. Such cooling is possible because the expected coolant temperatures of the internal combustion engine come to be below the ambient temperatures. For cooling the metal wall, an opening on the compression side is provided in the pump head; via a conduit in the common shaft of the electric motor, this opening together with the pump wheel creates a communication with the intake side of the pump. Thus via the rotor the full pressure difference of the pump is applied, so that a secondary flow of the fluid to be pumped, which is moved precisely past the cooling face of the motor housing, has been achieved.

[0017] Advantageously, the electric motor is disposed between the switch mechanism having the power electronics and the pump head. This makes a compact, space-saving construction of the motor pump of the invention possible. An electronically commutated direct-current motor, which can drive the pump, assures exact regulation of the coolant flow rate, for instance in a cooling or heating circuit of a motor vehicle with an internal combustion engine. This in turn makes a precisely adapted heat dissipation possible, and thus among other effects also enables optimal efficiency and fuel consumption of the vehicle engine.

DRAWING

[0018] In the drawing, one exemplary embodiment of the invention is shown, which is described in further detail in the ensuing description.

[0019] Shown are:

[0020]FIG. 1, a longitudinal section through an electric-motor-driven pump of the invention;

[0021]FIG. 2, a cross section through the stator of the electric motor of the electric-motor-driven pump of the invention; and

[0022]FIG. 3, a detail of the stator of the electric-motor-driven pump of the invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0023] The exemplary embodiment, shown in longitudinal section in FIG. 1, of an electric-motor-driven pump 10 of the invention comprises a pump head 12, which is driven by a brushless, electronically commutated electric motor 14, and a switch mechanism 16 for controlling the electric motor 14.

[0024] The pump head 12 has a pump housing 18, in which an impeller 22, secured to a drive shaft 20, is located in a pump chamber 11. The impeller 22 is provided with vanes 24 for transporting and increasing the pressure of a fluid to be recirculated. An opening 26 for aspirating the fluid in the direction of the arrow 28 leads into the pump housing 18. The pump housing also has an outlet opening 30, not completely shown in FIG. 1, on the compression side of the pump. The intake opening 26 discharges at the vanes 24 of the impeller 22 of the pump 10. In the exemplary embodiment of the motor pump 10 of the invention shown, the pump housing 18 is connected via a flange 32 to the motor housing 34 and sealed off via an O-ring 36, which is located between the two housing parts. For stable connection of the pump head 12 to the motor housing 30, various fastening options are conceivable, of which only screwing, riveting and adhesive bonding will be named here as examples.

[0025] The electric motor 14 of the pump 10 of the invention has a rotor 38, disposed in the motor housing 34, and a stator 40, radially surrounding the rotor 38. The stator 40 comprises a plastic carrier part 42, into which a plurality of soft iron teeth 44 forming the stator poles are injected directly. These soft iron teeth are embodied for instance in the form of sheet-metal lamination packets 46—as suggested in FIG. 1.

[0026]FIG. 2 shows a cross section through the stator 40. The plastic carrier part 42 and the pole teeth 44 injected into it can be seen. The plastic carrier part 42, on its inside 48 oriented toward the rotor 38 (not shown in FIG. 2 for the sake of simplicity), forms a completely closed plastic casing 50 of the stator 40. The plastic casing 50 is designed such that it seals off the rotor 38 located on the inside, that is, in the interstice 52 of the plastic carrier part 42, from the stator 40. The plastic casing 50 of the stator pole teeth 44 serves not only as a sealing wall 51 for the stator but also as a carrier form and winding body 54 for the windings 56 of the stator coils 58.

[0027]FIG. 3 in a detail shows one possible embodiment of the carrier form 54 for the windings 56 of the stator 40. The plastic casing 50 of the pole teeth 44 is shaped such that a stable receptacle is obtained for the windings 56 of the coil 58. Additional contact pockets 60 for the winding wire 62 can—as shown in FIG. 3—be formed—just like other required retaining means—directly on the plastic carrier part 42 of the stator 40 by a shaping process.

[0028] The stator 40 with its plastic carrier part 42 is secured in the axial direction, in a manner fixed against rotation, on one wall 64 of the motor housing 34 and is additionally sealed off from the motor housing 34 via sealing elements 66. The wall 64, remote from the pump head 12, of the motor housing 34 is embodied, in the exemplary embodiment shown, integrally with the motor housing 34 and has a plurality of retainers—embodied in this exemplary embodiment as pegs 68—for fixation of the stator 40. The housing wall 64 furthermore has a number of leadthroughs 70 for one or more electrical connections 72 connecting the electric motor 14 to the switch mechanism 16. The housing wall 64 can preferably—like the motor housing 34—be made of metal, so as to better absorb the forces and moments of the motor and to guarantee a secure fastening of the stator 40. For heat transfer reasons as well, a metal wall is an attractive option for the cooling wall 65. The housing wall 64 additionally has a retainer 74—embodied integrally in the exemplary embodiment—into which a first bearing 76 of the motor shaft 20 is placed.

[0029] According to the invention, the interior 52, encased by the plastic carrier part 42, of the stator 40 and the correspondingly covered region of the housing wall 64 of the motor housing 34 form a cup-shaped chamber 78, in which the rotor 38 of the electric motor 14 rotates. The rotor 38 is seated firmly on a shaft, which in this exemplary embodiment is also the drive shaft 20 of the pump impeller 22. The rotor 38 has permanent magnets 80 in the axial direction, which are distributed uniformly over its entire circumference. The cup-shaped chamber 78 forming a rotor chamber 82 is precisely large enough radially that the parts of the rotor remote from the axis revolve in the immediate vicinity of the inside 48 of the plastic casing 50 of the stator 40 but do not touch it. As a result of the plastic casing 50 of the invention on the stator 40, it is possible for the gap between the stator and the rotor 38 of the electric motor 14 to be kept very slight.

[0030] Toward the pump head 12, the rotor chamber 82 is closed off by a wall 84 and sealing elements 86. The wall 84 of the rotor chamber 82 carries a second bearing 88 for the drive shaft 20 of the pump 10. In addition, the wall 84 toward the pump head has an opening 90 toward the compression side of the pump 10.

[0031] Through the opening 90 on the compression side of the rotor chamber wall 84 toward the pump head, some of the fluid to be pumped can reach the rotor chamber 82 and both bathe and cool the rotor 28 and especially the bearings 76 and 88 of the drive shaft 20. The fluid that reaches the rotor chamber 82 also flows along the motor housing wall 64 toward the switch mechanism and cools it as well. Through a conduit 92 in the common drive shaft 20 of the motor 14 and pump head 12, the fluid then flows out of the rotor chamber 82 again in the direction of the arrow 94 and into the region of the intake-side opening 90 of the pump head 12.

[0032] The switch mechanism 16 for controlling and regulating the pump 10 of the invention is located on the side of the motor housing 34 remote from the pump head 12. In the exemplary embodiment shown, the switch mechanism 16 is joined integrally to the motor housing 34 and advantageously shares the housing wall 64 with it. On the side of the housing wall 64 remote from the motor 14, power elements 96 of the switch electronics 98 of the electric motor 14 are secured. These power elements 96, which can for instance be transistors, are mounted directly on the housing wall 64, in this exemplary embodiment, resulting in good thermal conductivity between these electrical components of the switch mechanism 16 and the wall 64. The heat produced by the electronics 98 can be given up quickly to the housing wall 64—which in the exemplary embodiment is of metal. However, it is also conceivable for the components of the switch element 16 that are to be cooled to be pressed against the housing wall 64 via springs instead. Direct adhesive bonding, with an electrically insulating adhesive, for thermal coupling of the electronic components 98 to the cooling wall 64 is also possible.

[0033] The housing wall 64 is furthermore bathed at least in part, toward the motor, by the fluid to be recirculated, so that according to the invention, a substantially improved heat dissipation is obtained for the components of the switch mechanism 16.

[0034] The switch mechanism 16 itself is to be closed via a lid 100, which in the exemplary embodiment is mounted directly on the motor housing 34 of the pump 10. The lid 100 can be slipped on, screwed on, riveted, adhesively bonded, or fastened securely and optionally reversibly by some other suitable technique to the motor housing 34. In the exemplary embodiment shown, the lid 100 of the switch mechanism 16 has a terminal 102 for externally supplying voltage to the motor pump 10 of the invention.

[0035] The invention is not limited to the exemplary embodiment of an electric-motor-driven pump described.

[0036] In particular, a sealing wall joined integrally to the stator can advantageously be employed as well. 

1. A pump, having a pump head (12), which has a pump chamber (11), having an electric motor (14), which drives the pump head (12) and has a stator (40) and a rotor (38), the rotor (38) being connected to the pump head (12) and being disposed in a rotor chamber (82) open toward the pump chamber (11), characterized in that the stator (40) is disposed radially around the rotor chamber (82), and the rotor chamber (82) is sealed off from the pump chamber (11) by a sealing wall (51) belonging to the stator (40) and by at least one wall (64) of the pump housing (18).
 2. The pump of claim 1, characterized in that the pump head (12), electric motor (14) and an electronic switch mechanism (16) for controlling the electric motor (14) are disposed in a common, in particular three-part pump housing (18).
 3. The pump of claim 1 or 2, characterized in that at least one wall (64) defining the rotor chamber (82) is embodied integrally with a motor housing (34) of the electric motor (14).
 4. The pump of claim 3, characterized in that the sealing wall (51) defining the rotor chamber (82) radially and belonging to the stator (40) seals off the rotor chamber (82) via elastic sealing means (66).
 5. The pump of one of the foregoing claims, characterized in that the sealing wall (51) defining the rotor chamber (82) radially is solidly connected to the stator (40).
 6. The pump of claim 5, characterized in that the sealing wall (51) is formed by a casing (50) of the stator (40), the casing being completely closed in the circumferential direction of the rotor chamber (82).
 7. The pump of claim 6, characterized in that the casing (50) of the stator (40), the casing being completely closed in the circumferential direction of the rotor chamber (82), is of plastic.
 8. The pump of claim 6 or 7, characterized in that pole teeth (44) of the stator (40) are injected into the casing (50) of the stator (40).
 9. The pump of claim 7 or 8, characterized in that the plastic casing (50) of the stator (40) is shaped such that it serves as a winding body (54) for stator windings (56).
 10. The pump of one of the foregoing claims, characterized in that the stator (40) is connected to the wall (64) of the motor housing (34).
 11. The pump of one of the foregoing claims, characterized in that at least one wall (64) enclosing the switch mechanism (16) is embodied integrally with the motor housing (34).
 12. The pump of one of the foregoing claims, characterized in that at least one electronic component (96) of the switch mechanism (16) is disposed on a cooling wall (65) that is cooled by a pumping medium.
 13. The pump of claims 11 and 12, characterized in that the cooling wall (65) is one wall (64) of the motor housing (34).
 14. The pump of claim 12 or 13, characterized in that a volumetric flow of the pumping medium flows from the compression side of the pump head (12) past the cooling wall (65) to the intake side of the pump head (12).
 15. The pump of one of the foregoing claims, characterized in that the electronic switch mechanism (16) is mounted on the opposite end of the motor housing (34) from the pump head (12).
 16. The pump of one of the foregoing claims, characterized in that the shaft of the electric motor (14) is simultaneously the drive shaft (20) of the pump head (12).
 17. The pump of claim 16, characterized in that the pumping medium flows through a conduit (92) in the drive shaft (20) of the motor (14) to the intake side.
 18. The pump of one of the foregoing claims, characterized in that the electric motor (14) is an electronically commutated direct-current motor.
 19. The pump of one of the foregoing claims, characterized in that the pump is water pump for use in motor vehicles.
 20. A method for producing a pump (10), in particular a fluid pump for the coolant or heating loop of a motor vehicle, in which the pump (10) has a pump head (12) and an electric motor (14) with a stator (40) and a rotor (38), characterized in that the stator (40) of the electric motor (14) that drives the pump head (12) is produced by spray-coating stator pole teeth (44), in particular with a plastic; and that upon injection of the stator pole teeth (44) into the plastic, the plastic casing (50) is shaped such that the stator pole teeth (44) come to be seated in a manner secure against relative rotation and firmly in the plastic casing (50); the plastic casing (50) is shaped as a carrier (54) of the stator windings (56); and the plastic casing (50) can seal off the stator (40) from the rotor chamber (82) of the electric motor (14), which rotor chamber is open toward the pumping medium. 